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Anatomy & Physiology An Integrative Approach 1e Michael McKinley Valerie O'Loughlin Theresa Bidle (Solutions Manual (Answer Key) All Chapters, 100% Original Verified, A+ Grade) All Chapters Solutions Manual Supplement files download link at the end of this file. Answer Key Chapter 1 Answers to “What Did You Learn?” 1. Comparative anatomy 2. Anatomy is the study of structure and form. Physiology is the study of how the structures function. 3. Cardiovascular 4. An anatomist will describe various tissues within the esophagus and their arrangement relative to each other. The physiologist will focus on how the tissues are involved in, and possibly interact, during the process of swallowing. 5. The ability of organisms to respond to stimuli such as changes in either their external or internal environment provides them with a mechanism for maintaining a constant internal environment, even as the environment around them changes. 6. A higher level of organization does contain all of the levels beneath it. Each level of organization is a function of the arrangement of its subsequent subunits, which are in turn a function of the organization of their subunits. Therefore, each level organization is dependent on the organization of all of the levels below. 7. The urinary system is responsible for filtering and removing waste products from the blood. 8. A transverse plane, also called a horizontal or cross-sectional plane, would divide the mouth into superior and inferior sections. 9. Proximal 10. The term antebrachial refers to the forearm, the portion of the upper limb between the elbow and wrist. 11. The lungs are located within the thoracic cavity. The serous membranes surrounding them consist of a parietal pleura lining the inside of the body wall and a visceral pleura lining the individual lungs. 12. Epigastric 13. A homeostatic system consists of a receptor such as a sensory neuron in the skin or a stretch receptor within a muscle that detects either an internal or external stimulus; a control system that integrates the input from the receptor such as the brain or an endocrine gland; and an effector such as a muscle or a gland that causes changes in response to the stimulus. 14. The body may respond to a drop in temperature by decreasing the diameter of blood vessels carrying blood to the surface of the skin, thereby decreasing the amount of heat lost to external environment. Another response involves stimulation of skeletal muscles, causing “shivering” and thereby generating heat internally. 15. Negative feedback systems involve responses that are in opposition to the stimulus, thereby maintaining the environment near the set point or normal level. Conversely, positive feedback systems entail a series of responses each increasing in intensity until a climax event is reached, at which point the system will return to homeostasis. 16. Diabetes, an inability of the body to maintain blood sugar levels, may result in damage to anatomical structures throughout the body due to high levels of glucose.

Answers to “Do You Know the Basics?” 1. B Feedback: Surface anatomy correlates superficial markings on the surface of the body and skin to deeper anatomical features. 2. C Feedback: Organs are often composed of several tissue types working in concert to perform a common function. 3. A Feedback: An organism’s metabolism is the sum of all of its biochemical reactions.

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4. C Feedback: A midsagittal or median plane separates the body into equal right and left halves as compared to simply a sagittal section, which separates the body into unequal right and left portions. There can be numerous sagittal planes but only one possible midsagittal section along the midline of the body. 5. D Feedback: The term proximal is used to describe the position of a structure on an appendage closest to the point of attachment to the trunk. Although in standard anatomical position a structure that is proximal is often also superior, proximal is the correct term for describing the position along an appendage. The term superior may be used to describe positions along the axis of the body, closer to the head. 6. A Feedback: The patellar region is the anterior portion of the knee. The popliteal region is the posterior portion of the knee. 7. A Feedback: The diaphragm comprises the barrier between the superior thoracic cavity and the inferior abdominal cavity. The pelvic cavity is located inferior to the superior edges of the pelvic bones. 8. D Feedback: The pleural cavity surrounding the lungs consists of a parietal pleura lining the internal walls of the thoracic cavity and a visceral pleura lining the surface of the lungs. 9. B Feedback: Homeostasis is an automated process for maintaining a constant internal environment. 10. D Feedback: The effector increasing the stimulus is an example of positive feedback. In a negative feedback system, the response moves the system in opposition to the stimulus, back toward the set point.

11. Anatomy is the study of structure and form, whereas physiology is the study of how the structures function. It is important to understand the anatomy of a structure in order to understand how it performs its function. Conversely, understanding the function of an anatomical feature helps to put into perspective the significance of its arrangement. 12. The simplest level of organization within an organism is found at the chemical level and is composed of atoms and molecules. At the cellular level of organization, molecules are organized into cells and subcellular components, forming the basic units of life. Groupings of similar cells performing similar functions are referred to as tissues, and groups of tissues may be found working in concert, forming organs at the organ level of organization. Related groups of organs working together in order to coordinate activities within the organism are called organ systems. 13. A hierarchical organization, metabolism, growth and development, responsiveness, regulation, and reproduction are characteristics common to all living organisms. All living things are arranged in a hierarchical manner with increasing levels of complexity from molecules to cells. They are capable of metabolism, growth and development, and responsiveness to stimuli. They are also able to regulate their internal environment in order to maintain homeostasis, ultimately surviving long enough to reproduce. 14. The human body consists of eleven organ systems. They are the integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, urinary, digestive, and reproductive systems. 15. A body in anatomical position is standing upright with the feet flat on the floor. The upper limbs are at the side of the body with palms facing anteriorly. The head is level and the eyes are looking forward. 16. The forearm is the antebrachial region, the wrist is the carpal region, the chest is the thoracic region, the armpit is the axillary region, the thigh is the femoral region, and the entire foot is the pes. 17. The cranial cavity and vertebral canal are located within the posterior aspect of the body. The cranial cavity houses the brain and the vertebral canal contains the spinal cord.

18. The serous membranes are found lining the compartments of the ventral cavity of the body. They consist of a parietal layer lining the inside of the body wall and a visceral layer covering internal organs. In between the two membranes is a potential space, the serous cavity, which contains serous fluid. 19. A homeostatic system consists of a receptor that detects an internal or external stimulus, a control system that integrates the input from the receptor, and an effector such as a muscle or a gland that causes changes in response to the stimulus. 20. Negative feedback systems involve responses that are in opposition to the stimulus, thereby maintaining the environment near the set point or normal level. Conversely, positive feedback systems entail a series of responses, each increasing in intensity until a climax event is reached, at which point the system will return to homeostasis.

Answers to “Can You Apply What You’ve Learned?” 1. B Feedback: The pain is coming from a region below the umbilicus, hence it is in the lower portion of the abdomen and it is located on the right side. It is therefore in the right lower quadrant. 2. D Feedback: The right iliac region is located just medial to the pelvic bones. 3. B Feedback: X-rays are not absorbed by soft tissue such as the appendix. They are usually used to visualize dense structures. 4. B Feedback: Sweat glands release heat at the surface of the skin. 5. B Feedback: Serotonin is a neurotransmitter responsible for regulating both pathways associated with depression in the brain and gastric motility in the stomach. Drugs such as SSRIs are used to treat depression in individuals with low levels of serotonin in the brain by inhibiting its reuptake by neurons. Because the SSRI drugs cannot specifically target the brain, they also have an effect within the digestive system, causing nausea and diarrhea.

Answers to “Can You Synthesize What You’ve Learned?” 1. Lynn has broken the bones within her forearm, the radius and ulna. She has an abrasion on her chin as well as bruising on her buttocks and thigh. 2. The epinephrine counteracted the effect of the bee sting, acting in opposition to the stimulus; it was therefore an example of negative feedback. 3. X-rays and CT scans are optimal for visualizing dense tissues such as tumors. An MRI or ultrasound would be better suited for examining soft tissues.

Chapter 2 Answers to “What Did You Learn?” 1. The mass of an atom is determined by the combined number of protons and neutrons within its nucleus. The charge is a function of the ratio of protons to electrons. 2. The nucleus of a chlorine atom consists of 17 protons and 17 neutrons. The electrons are arranged into three separate shells; the first shell closest to the nucleus contains two electrons, the second shell contains eight electrons, and the third outer shell contains seven electrons for a total of 17 electrons. 3. Isotopes are atoms of the same element that differ in their number of neutrons. In a radioisotope the extra neutrons will decay and be released as radiation. 4. Elements such as the noble gases have satisfied the octet rule by having a complete outer electron shell and are therefore not reactive. Other elements may form bonds in order to satisfy the octet rule and fill their outer shells. 5. Common cations of the human body include sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), magnesium ions (Mg2+), and hydrogen ions (H+). Common anions include chloride ions (Cl-), bicarbonate ions (HCO3-), and phosphate ions (PO43-). 6. Hydrogen (H), sodium (Na), magnesium (Mg), potassium (K), and chloride (Cl) 7. In order to satisfy the octet rule, atoms with only one electron in their outer shell may give up the electron, resulting in a slightly positive cation with a full outer shell. Conversely, atoms with seven electrons in their outer shell may accept an electron from another atom, becoming a slightly negative anion but with a full outer shell. 8. Ionic bonds are formed due to an attraction between ions with different charges; therefore, two positive cations cannot form an ionic bond with each other, nor can two negatively charged anions. 9. The molecular formula exhibits the type and number of atoms in a molecule; the structural formula also provides information on how the atoms are arranged. 10. Isomers are molecules composed of the same type and number of elements, but are arranged differently. 11. A covalent bond is formed when atoms share electrons in their outer orbitals in order to satisfy the octet rule. 12. Oxygen atoms each contain six electrons in their outer orbitals and each have room for two more. In a double bond they share two pairs of electrons and thereby each satisfies the octet rule. 13. A covalent bond between atoms of the same element will result in an equal distribution of electrons across the molecule since both atoms are equally electronegative, resulting in a nonpolar molecule. Molecules composed of different atoms result in an unequal distribution of charge across the molecule, where more electronegative atoms have a slightly negative charge and less electronegative atoms are slightly less negative. Since oxygen and hydrogen atoms are nearly equal in terms of electronegativity, atoms of these two different elements can also form nonpolar covalent bonds. 14. Both molecular oxygen (O2) and carbon dioxide (CO2) are nonpolar molecules. 15. A hydrogen bond is an intermolecular attraction between a slightly positive hydrogen atom and another slightly negative atom. 16. Hydrogen bonding is an important factor behind many of the properties of water molecules. 17. Surfactant is required to break cohesive attraction between water molecules in the alveoli of the lungs. The high heat of vaporization of water molecules makes them an effective mechanism for dissipating heat at the surface of the skin. 18. Nonelectrolytic molecules such as glucose do not dissociate in water. Electrolytes such as sodium chloride (NaCl) disassociate into constituent ions in an aqueous environment, forming a solution capable of conducting electricity. 19. In an aqueous environment, amphipathic molecules such as phospholipids will orient themselves so that their hydrophobic domains face each other while the hydrophilic domains are exposed to water. This is the basis behind the arrangement of phospholipids within a phospholipid bilayer.

20. Each water molecule can disassociate into one negatively charged hydroxyl ion and one positively charged hydrogen ion, leaving it with an equal distribution of positive and negative charges, which is considered neutral. 21. An acid is capable of releasing hydrogen ions in an aqueous environment. 22. pH is the relative measure of hydrogen ions in a solution. 23. Buffers maintain the pH of physiologic solutions within a normal range by absorbing hydrogen ions when an acid is added or hydroxyls when a base is added to the solution. 24. Blood is a suspension of formed elements that settle out of solution when a sample is left standing. 25. Blood is also considered a colloid because it contains numerous proteins and a solution because of its numerous dissolved solutes, such as ions and sugars. 26. The concentration of a solution may be expressed as either the mass of solute/volume of solution, percent of mass of solute in 100 milliliters of solution, moles of solute/liter of solution (molarity), or the moles of solute/kilogram of solvent (molality). 27. Biological molecules typically contain carbon (C), hydrogen (H), and oxygen (O) and in some cases may also contain nitrogen (N), phosphorus (P), and sulfur (S). Of these, hydrogen is the only one capable of forming a common biological ion. 28. Carboxylic acids and phosphates are capable of acting as acids. 29. A polymer is composed of repeating monomer subunits. Proteins are composed of amino acids, carbohydrates are composed of simple sugars, and nucleic acids are composed nucleotides. 30. Lipids are hydrophobic molecules and do not typically dissolve in water. 31. Phospholipids contain both a hydrophilic head group and a pair of hydrophobic fatty acid tails, making them ideally suited for forming cellular membranes. 32. Glycogen can be found within the liver and muscle tissue of animals and is composed of repeating glucose subunits. 33. Fructose, glucose, and galactose are monosaccharides. Sucrose, maltose, and galactose are disaccharides. Glycogen and starch are polysaccharides. 34. Nucleic acids store and transfer genetic information within cells. 35. RNA molecules contain a ribose sugar rather than the deoxyribose sugar of DNA. The nucleotide thymine is present in DNA. In its place, RNA contains the nucleotide uracil. 36. Amino acids are the monomers of a protein and are held together by peptide bonds. 37. A dipeptide consists of 2 amino acids, an oligopeptide contains 3 to 20 amino acids, a polypeptide contains 21 to 199 amino acids, and a protein consists of 200 or more amino acids. The term protein is generally used to refer to any of these molecules. 38. The R group of leucine is a short nonpolar hydrocarbon, making it a nonpolar amino acid. 39. The tertiary structure of a protein is its three-dimensional shape. The quaternary structure describes the interaction of two or more polypeptide chains within a functional protein. 40. Denaturing a protein changes its conformation and often affects its activity. Exposure of a protein to hydrogen ions can denature a protein by disrupting electrostatic interactions such as ionic bonds within the molecule.

Answers to “Do You Know the Basics?” 1. C Feedback: Isotopes are atoms of the same element that differ in the number of neutrons.

2. A Feedback: Lipids are hydrophobic molecules and are not soluble in water. 3. C Feedback: Water has a high specific heat, allowing it to absorb energy without changing temperature. Conversely, the high heat of vaporization for water allows it to dissipate a large amount of energy during evaporative cooling of the skin. 4. D Feedback: A pH less than 7.0 is acidic and a pH greater than 7.0 is basic. 5. D Feedback: The formed elements of blood act as a suspension. Dissolved proteins in the plasma act as a colloid. The numerous dissolved solutes also make it a solution. 6. A Feedback: Triglycerides are not considered polymers because they are not composed of repeating monomer subunits. 7. C Feedback: Glucose is stored in animal tissues as glycogen. 8. B Feedback: Although phosphates which contain phosphorus are common ions in the body, phosphorus itself is not a common ion. 9. B Feedback: A hydrogen bond is an intermolecular attraction between a slightly positive hydrogen atom and another slightly negative atom. 10. B Feedback: Denaturing a protein changes its conformation. Excessive denaturation can permanently affect protein structure and possibly its function as well. 11. Common cations of the human body include sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), magnesium ions (Mg2+), and hydrogen ions (H+). Common anions include chloride ions (Cl-), bicarbonate ions (HCO3-), and phosphate ions (PO43-). 12. A polar molecule such as water results from an unequal distribution of electrons between covalently bonded atoms. Oxygen, the more electronegative of the atoms, will have a stronger pull on the electrons and will thus have a slightly more negative charge around it. The hydrogen atom will be relatively more positive (or less negative). Two water molecules can form a hydrogen bond between their opposite poles, whereby relatively positive hydrogen will be attracted to relatively negative oxygen on the other molecule. 13.

14. Covalently bonded compounds such as glucose will not dissociate when dissolved in water; however, they will remain in solution after the mixture is no longer agitated. Ionic compounds such as sodium chloride (NaCl) will disassociate in water. The polar water molecules will disrupt the electrostatic interactions between sodium and chloride ions, thereby separating them. 15. An acid contributes hydrogen ions to a solution, making it more acidic; a base absorbs hydrogen ions from a solution, making it more basic. pH is the measure of hydrogen ions in a solution. A buffer is a solution capable of absorbing either hydrogen or hydroxyl ions, thereby maintaining its pH when acids or bases are added.

16. The concentration of a solution may be expressed as either the ratio of the mass of solute compared to the volume of the solution, as the percent of mass of solute in 100 milliliters of solution, as the number of moles of solute per liter of solution (molarity), or the number of moles of solute per kilogram of solvent (molality). 17. Proteins are composed of amino acids; carbohydrates are composed of simple sugars; nucleic acids are composed of nucleotides; and lipids consist of fatty acids. 18. The catabolism of either the nitrogenous bases present in nucleotides or the amine groups of amino acids may result in nitrogenous waste that must be removed from the body by the kidneys. 19. In an aqueous environment, amphipathic molecules such as phospholipids will orient themselves so that their hydrophobic domains face each other while the hydrophilic domains are exposed to water. This is the basis behind the arrangement of phospholipids within a phospholipid bilayer. 20. Denaturing a protein changes its conformation and often affects its activity. Exposure of a protein to a pH outside of its norm or an increase in temperature can denature a protein by disrupting electrostatic interactions such as ionic bonds within the molecule.

Answers to “Can You Apply What You’ve Learned?” 1. C Feedback: Surfactant is a detergent that prevents hydrostatic interactions between water molecules, thereby preventing the lungs from collapsing. Premature babies often lack the ability to produce surfactant and are at risk for respiratory problems. 2. B Feedback: Electrolytes such as sodium chloride (NaCl) dissociate into constituent ions in an aqueous environment, forming a solution capable of conducting electricity. Nonelectrolytic molecules such as glucose do not dissociate in water. 3. B Feedback: Isotopes are atoms of the same element that differ in their number of neutrons. In a radioisotope the extra neutrons will decay and be released as radiation, which may be measured or visualized during a diagnostic test. 4. D Feedback: Calcium ions are an important structural component of bone tissue. 5. C Feedback: Proteins consist of covalently bonded amino acids held together by peptide bond.

Answers to “Can You Synthesize What You’ve Learned?” 1. High-energy radiation can affect bonds within nucleotides, thereby damaging DNA. 2. Acidosis is an increase in the number of hydrogen ions in the blood, resulting in a lower pH. The increasing number of hydrogen ions may start to damage the hydrostatic interactions holding proteins together, destroying tertiary structure and denaturing the proteins. 3. The drug would regulate the levels of the monosaccharide glucose within the blood.

Chapter 3 Answers to “What Did You Learn?” 1. Kinetic energy represents a change in position. Movement of sodium ions along a concentration gradient or the movement of electrons from higher to lower energy state are both examples of kinetic energy. 2. The movement of muscle is an example of mechanical energy, a form of kinetic energy. 3. Even though energy can neither be created nor destroyed, it can change forms. Such transformations are rarely completely efficient, resulting in the release of some of the energy as heat, the least organized form of energy. 4. Reactants are the substrates prior to a reaction. The reactants are converted to products during the reaction. 5. This synthesis reaction would be anabolic, because it would result in a more complicated structure. It would also be endergonic, since it would require an input of energy. 6. ATP is produced by exergonic reactions. It is often used to couple exergonic reactions to endergonic reactions that require an input of energy. 7. When equilibrium is disturbed in a reversible reaction, the system will adjust driving the reaction toward either the reactants or the products, until equilibrium is reestablished. 8. Although raising the temperature of a reaction increases the kinetic energy of molecules, in a biological system this can decrease the rate of the reaction by denaturing the enzymes involved. 9. Enzymes lower the energy of activation required for a reaction. 10. The active site of an enzyme is the temporary binding site of the substrate on the enzyme. 11. Enzymes are proteins that catalyze metabolic reaction by lowering the activation energy necessary for the reaction. The structure of the protein directly affects its affinity for its specific substrate. Inorganic cofactors are often associated with enzymes facilitating their actions. Organic cofactors (coenzymes not attached to the protein) such as NAD+ and FAD+ may also be required to complete enzymatic reactions. 12. The name of an enzyme usually describes its action and usually contains the suffix -ase. 13. The rate of an enzyme-catalyzed reaction will increase as the concentration of substrate is increased, until all of the enzyme molecules are saturated. Decreasing temperature from an enzyme’s optimum range will gradually decrease activity by decreasing the kinetic energy of the system. Increasing temperature will have a more sudden negative effect on enzyme function as the molecule is denatured. Changing pH of an enzymatic reaction will readily denature the protein as the excessive hydrogen or hydroxyl ions interfere with electrostatic interactions within the enzyme, denaturing it. 14. Competitive inhibitors affect enzyme activity by competing with substrates at the active site. Noncompetitive inhibitors modulate the shape of the enzyme by binding to an allosteric binding site, outside of the active site, thereby affecting the overall shape of the enzyme and its function. 15. A metabolic pathway consists of a series of enzyme-catalyzed reactions. Often the final product of the pathway serves as an allosteric inhibitor of enzymes within the pathway, providing for negative feedback within the system. 16. Phosphorylation and dephosphorylation entail the addition or removal of phosphates, respectively. Addition of a phosphate to an enzyme affects the shape, and therefore the function, of the enzyme. 17. C6H12O2 + 6 O2 → 6 CO2 + 6 H2O. The catabolism of glucose, an exergonic reaction, results in the production of six molecules of carbon dioxide. Oxygen acts as the final electron acceptor in the process which involves the energy from the release of CO2 to synthesize ATP. 18. Cellular oxidation begins with glycolysis in the cytosol of the cell. The remaining steps are the intermediate reactions, the citric acid cycle, and the electron transport chain which occur within the mitochondria.

19. Glycolysis is an anaerobic process that occurs in the cytosol of a cell. The net reaction entails the synthesis of two 3-carbon pyruvate molecules from one 6-carbon molecule of glucose. The reaction involves the initial input of two molecules of ATP and yields four, for a net yield of two molecules of ATP. Two molecules of NAD+ are also reduced to form NADH + H+ from electrons and protons released during the oxidation of glucose. 20. Under aerobic conditions, in the presence of oxygen, pyruvate enters the mitochondria to complete oxidation. Under anaerobic conditions pyruvate will be converted to lactate. 21. The intermediate stage of cellular respiration is an aerobic process that links glycolysis with the citric acid cycle. It is catalyzed by pyruvate dehydrogenase and involves the decarboxylation of pyruvate to yield carbon dioxide. The remainder of the molecule is combined with coenzyme A to form the acetyl CoA complex. Two molecules of NAD+ are reduced to form NADH + H+ from electrons and protons released during the oxidation of pyruvate to acetyl CoA. 22. The citric acid cycle is an aerobic process that occurs within the matrix of mitochondria. Assuming one molecule of glucose, the process entails the catabolism of one acetyl CoA molecule, yielding one oxaloacetate and two molecules of carbon dioxide. The oxidation of acetyl CoA also yields three molecules of NADH + H+, one molecule of FADH2, and one molecule of ATP. 23. Cellular respiration of one molecule of glucose yields two molecules of ATP and two molecules of NAHD during glycolysis, and two molecules of NADH during the intermediate stage. The citric acid cycle yields six more molecules of NADH + H+, two molecules of FADH2, and two more molecules of ATP. 24. NADH and FADH2 couple the oxidation of glucose and subsequently pyruvate to the electron transport chain. 25. Oxidative phosphorylation entails the transfer of electrons from NADH and FADH2 to the electron transport chain, the establishment of a proton gradient through the use of energy from electron passed along the chain, and finally the diffusion of the proton gradient through the ATP synthetase to form bonds between ADP and Pi. 26. Glycolysis yields two molecules of ATP for every one molecule of glucose. Under aerobic conditions the complete oxidation of one molecule of glucose yields 36 molecules of ATP. 27. Under anaerobic conditions pyruvate is converted to lactate in the cytosol. This facilitates the regeneration of two molecules of NAD+ which can then be utilized to continue with the glycolysis of more glucose, yielding ATP. 28. The beta-oxidation of fatty acids converts them to acetyl CoA, which can only be consumed during the aerobic stage of cellular respiration.

Answers to “Do You Know the Basics?” 1. A Feedback: Energy from the hydrolysis of ATP (a chemical reaction) is used to power the sliding of filaments during a muscle contraction (a mechanical process). 2. A Feedback: Oxidation-reduction reactions involve the exchange of electrons between the oxidizing and the reducing agent. 3. B Feedback: Increasing pH interferes with electrostatic interactions within the enzyme, causing denaturation of the molecule. 4. C Feedback: Since ATP does not bind to the active site of phosphofructokinase, it is not a competitive inhibitor. It is an example of an allosteric/noncompetitive inhibitor. 5. D Feedback: Enzymes are very specific for their substrate and are therefore only involved in very particular reactions. 6. A Feedback: Glycolysis yields two molecules of pyruvate from one molecule of glucose.

7. D Feedback: NAD+ and FAD+ are coenzymes involved in oxidation-reduction reactions where they shuttle electrons away from the substrate. 8. A Feedback: Glycolysis is able to continue under anaerobic conditions, yielding two molecules of ATP, two molecules of NADH, and one molecule of lactate. 9. C Feedback: One molecule of glucose may yield 2 molecules of ATP under anaerobic conditions and 36 molecules of ATP if oxygen is present. 10. D Feedback: Oxidative phosphorylation entails the transfer of electrons from NADH and FADH2 to the electron transport chain, the establishment of a proton gradient through the use of energy from electrons passed along the chain, and finally the diffusion of the proton gradient through the ATP synthase to form bonds between ADP and Pi. 11. Energy stored in glycogen or triglycerides represents chemical energy, a form of potential energy. Electrical energy such as the propagation of an impulse along a neuron, the mechanical energy of a muscle contraction, or sound energy vibrating either the tympanic membrane in the ear or the vocal folds of the larynx are all examples of kinetic energy. 12. Chemical reactions are classified as either reactions that cause a structural change to a molecule, reactions that change the chemical energy of a molecule, or reactions that are either reversible or irreversible. An oxidation-reduction reaction is an exchange reaction and would therefore be an example of a change in chemical structure. 13. ATP is oxidized to ADP and Pi, releasing energy which is used to do work in the cell. The regeneration ATP from ADP and Pi is then coupled to the oxidation of hydrocarbons during cellular respiration. 14. Enzymes are globular proteins that catalyze metabolic reaction by lowering the activation energy necessary for the reaction. The structure of the protein directly affects its affinity for its specific substrate. Thus the slightest conformational change due to a change in temperature or pH can readily affect enzyme function. 15. A metabolic pathway consists of a series of enzyme-catalyzed reactions. Often the final product of the pathway serves as an allosteric inhibitor of enzymes within the pathway, causing a conformation change in the protein. This rearrangement may affect the affinity for the substrate at the enzymes' active site, thereby providing for negative feedback within the system. 16. Glycolysis is an anaerobic process that occurs in the cytosol of a cell. The net reaction entails the synthesis of two 3-carbon pyruvate molecules from one 6-carbon molecule of glucose. The reaction involves the initial input of two molecules of ATP and yields four, for a net yield of two molecules of ATP. Two molecules of NAD+ are also reduced to form NADH + H+ from electrons and protons released during the oxidation of glucose. 17. Under aerobic conditions, in the presence of oxygen, pyruvate enters the mitochondria to complete oxidation. Under anaerobic conditions pyruvate will be converted to lactate. 18. Oxygen serves as the final electron acceptor of the electron transport chain during oxidative phosphorylation. Molecular oxygen (O2) in the mitochondrial matrix is split and each oxygen atom along with electrons from the electron transport chain combine with two hydrogen ions, yielding a molecule of water. 19. The carbon in carbon dioxide is liberated from the hydrocarbon backbone of sugars or other organic molecules used to fuel cellular respiration. 20. Healthy respiratory and cardiovascular systems provide metabolically active tissues with adequate oxygen to drive efficient aerobic respiration. Tissues deprived of oxygen will not be able to burn fuels efficiently nor produce adequate amounts of ATP.

Answers to “Can You Apply What You’ve Learned?” 1. C Feedback: The enzyme tyrosinase is required to convert tyrosine to melanin.

2. D Feedback: Decreased respiratory function will lead to a deficiency in oxygen and thus anaerobic respiration, not aerobic respiration. 3. B Feedback: The reversible reaction will be driven toward the synthesis of carbonic acid (H2CO3), which will spontaneously decompose to hydrogen (H+) and bicarbonate ions (HCO3). The result will be a decrease in the pH of the blood, a condition known as respiratory acidosis. 4. D Feedback: Individuals with anemia, asthma, or heart failure would have a diminished capacity for delivering oxygen to tissues. An athlete would have optimized capacity for oxygen transport and therefore normal ATP production. 5. C Feedback: By uncoupling the proton gradient within the intermembrane space of mitochondria from the synthesis of ATP, the majority of energy from foods would be lost as heat rather than stored as chemical energy.

Answers to “Can You Synthesize What You’ve Learned?” 1. An asthma attack would decrease Tiffany’s ability to ventilate her lungs with air. The result would be a decrease in the amount of oxygen reaching her tissues and less energy production because of a decrease in aerobic respiration. 2. A patient’s aerobic fitness corresponds directly to the patient's ability for ATP production. Increased fitness provides for more efficient delivery of oxygen to tissues, allowing for effective aerobic respiration of fuels. 3. If inhibition of a metabolic pathway does not occur, the product will accumulate. This will drive the reaction in the opposite direction, unless the product is removed or metabolized as part of another pathway.

Chapter 4 Answers to “What Did You Learn?” 1. Electron microscopy utilizes electrons rather than photons of light to visualize the specimen, providing greater resolution. 2. The typical cell ranges from 7 to 120 μm in diameter. 3. The plasma membrane is the outer (phospholipid bilayer) covering of the cell. The genetic material is located within the nucleus. Aside from the nucleus, everything else within the plasma membrane is in the cytoplasm. 4. The plasma membrane defines the boundary of the cell and maintains its integrity. 5. The plasma membrane consists of phospholipid molecules configured into a bilayer. The hydrophobic tails of each layer are oriented toward each other, while the hydrophilic (polar) heads are exposed to aqueous environments. Thus the cytosol is isolated from the extracellular (interstitial) fluid by the phospholipid bilayer. 6. Transport proteins are integral membrane proteins that function as carriers, channels, or pumps to facilitate movement through the plasma membrane. 7. O2 and CO2 do not require transporters. They may pass through the phospholipid bilayer by simple diffusion. 8. Small ions and polar molecules may be transported across the plasma membrane by facilitated diffusion. Small ions diffuse through pores or channels, whereas small polar molecules require carrier proteins. 9. Osmosis is the passive movement of water through a semipermeable membrane. 10. The tonicity of a cell placed into an isotonic solution will not change. A cell placed into a hypertonic solution will lose tonicity as more water moves out of the cell than back into the cell. The converse will occur when a cell is placed into a hypotonic solution— tonicity will increase as more water moves into the cell than is moving out. 11. The net movement of water will be toward the hypertonic solution. 12. Secondary active transport often couples the movement of one molecule down its concentration gradient to movement of another molecule against its gradient. 13. A white blood cell ingesting a microbe is an example of phagocytosis. 14. Interactions between the glycocalyxes of two cells may be seen during the recognition of cells by the immune system, during the interaction of eggs and sperm at the onset of fertilization, or during the contact inhibition of growth within tissues. 15. Enzyme receptors act as kinases directly in response to a stimulus; G protein–coupled receptors activate a downstream kinase through a second messenger. 16. Lysosomes and peroxisomes are involved in “digestion” within the cell. Lysosomes enzymatically degrade various substrates. Peroxisomes contain the mechanisms for oxidation of fatty acids. Mitochondria in the cell are responsible for the majority of ATP synthesis. 17. The plasma membrane forms vesicles during endocytosis. Vesicles formed by the endoplasmic reticulum and Golgi apparatus may be involved in exocytosis. 18. Proteasomes are non-membrane-bound organelles, responsible for the digestion of proteins. 19. Microvilli tend to be much shorter and more densely packed than cilia. Although both entail a fold within the plasma membrane of a cell organized by the cytoskeleton, cilia involve a mechanism for movement whereas microvilli usually serve to increase the surface area of the cell. 20. Although both desmosomes and tight junctions hold adjacent cells together, only tight junctions prevent the movement of substance in between the neighboring epithelial cells. 21. Nuclear pores permit the movement of ions in or out of the nucleus as well as the movement of RNA out of the nucleus.